1. Field of the Invention
The present invention relates generally to the downhole well operations, and more particularly to downhole chemical injection for intelligent completions.
2. Background Art
Hydrocarbon fluids such as oil and gas are produced from subterranean formations by drilling a well to penetrate the hydrocarbon-bearing formation. After drilling, the wells are typically completed with various devices downhole to facilitate the production of the hydrocarbons. In an intelligent completion system, various sensors, pumps, and flow control valves are included. In addition, an intelligent completion system may include fully automated measurement and control systems that optimizes reservoir economics without human intervention.
When a broad pay zone or multiple pay zones is completed, the intelligent completion system may include multiple production zones. FIG. 1 shows an example of two adjacent producing zones 10 and 12. The wellbore is cased with casing 16 that has perforations 18 and 19, respectively, in zones 10 and 12. A bottom hole assembly 11 includes an upper packer 13 and a bottom packer 14. There are an upper screen 15, a lower screen 17, and a zone isolation packer 10a separating zones 10 and 12. Annulus 11a is defined between the casing 16 and the tubing 12a and between packers 13 and 14.
When formation fluids from formations come into contact with a pipe, valve or other production equipment in a wellbore, or when there is a decrease in temperature, pressure, or change of other conditions, waxes and/or asphaltines in the formation fluids may precipitate or separate out. Over time, deposits such as scale, wax, or asphaltine, etc., may build-up on surfaces of downhole components and impede their function and/or efficiency. To address the issue of deposit build-up, chemicals may be injected into production tubing to remove, reduce or inhibit the deposit material inside the tubing or on downhole devices. For example, a control line may be run from the surface to an injection point located in the completion to convey the injected chemical downhole into a production stream. One common practice is to have one or more injection points provided upstream a production packer.
In intelligent completion well systems, multiple flow control valves are run to control the production from multiple zones. However, these various valves may not function in the event of scale build up around moving surfaces. Running control lines from the surface to remedy these situations may not be practical when multiple zones are included in a completion. Therefore, chemical injection systems suitable for preventing and/or reducing deposit build-up in intelligent completion are needed.